Speaker system

ABSTRACT

A speaker system comprises a housing that includes a front wall with a plurality of openings, and first and second exterior sidewalls. A plurality of vertically arranged speakers are each placed into an associated one of the plurality of openings and secured to the housing. A hemispherical concave interior wall is positioned in back of the plurality of speakers and within said first and second sidewalls to disperse and attenuate audio waves within the housing. The housing may also include a tuned, dampening bisector that is mounted to the hemispherical concave interior wall positioned in back of said plurality of speakers and within the first and second sidewalls. The bisector is preferably located at the center of the hemispherical concave interior wall. A rear exterior wall defines a back of the speaker system and the front wall defines a front of the speaker system. The first and second interior sidewalls extend from front to back and preferably taper inward from back to front of the speaker system, wherein the first and second interior sidewalls each mate with the hemispherical concave interior wall. The plurality of speakers preferably include mid-range drivers and tweeters. For example there may be two tweeters associated with every mid-range driver. In one embodiment there are for example twenty-one mid-range driver and forty-two tweeters, wherein two tweeter openings are adjacent to an associated one of the mid-range openings. The speakers are arranged electrically in a series/parallel configuration. For example, several mid-range speakers/drivers are arranged in a series configuration to provide a mid-range subarray, and the number of mid-range drivers placed into each sub-array is selected such that the total Q factor for the sub-array is approximately one.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from the provisional applicationdesignated serial number 60/115,283 filed Jan. 6, 1999 and entitled“Loudspeaker System”. This application is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to loudspeakers, and in particularto a loudspeaker system comprising a multi-driver array.

[0003] Audiophiles are constantly seeking improved speaker systems fortheater (e.g., home theaters) and listening rooms that provide goodaudio performance. Prior art speaker systems have been limited by theirdynamic frequency response and frequency selective dispersion.

[0004] Therefore, there is a need for an improved speaker system.

SUMMARY OF THE INVENTION

[0005] Briefly, according to the present invention, a speaker systemcomprises a housing that includes a front wall with a plurality ofopenings, and first and second exterior sidewalls. A plurality ofvertically arranged speakers are each placed into an associated one ofthe plurality of openings and secured to the housing. A hemisphericalconcave interior wall is positioned in back of the plurality of speakersand within said first and second sidewalls to disperse and attenuateaudio waves within the housing.

[0006] The housing may also include a tuned, dampening bisector that ismounted to the hemispherical concave interior wall positioned in back ofsaid plurality of speakers and within the first and second sidewalls.The bisector is preferably located at the center of the hemisphericalconcave interior wall. A rear exterior wall defines a back of thespeaker system and the front wall defines a front of the speaker system.The first and second interior sidewalls extend from front to back andpreferably taper inward from back to front of the speaker system,wherein the first and second interior sidewalls each mate with thehemispherical concave interior wall.

[0007] The plurality of speakers preferably include mid-range driversand tweeters. For example there may be two tweeters associated withevery mid-range driver. In one embodiment there are for exampletwenty-one mid-range driver and forty-two tweeters, wherein two tweeteropenings are adjacent to an associated one of the mid-range openings.The speakers are arranged electrically in a series/parallelconfiguration.

[0008] According to another aspect of the invention, several mid-rangespeakers/drivers are arranged in a series configuration to provide amid-range sub-array. The number of mid-range drivers placed into eachsub-array is selected such that the total Q factor for the sub-array isapproximately one.

[0009] Advantageously, the present invention provides improved transientresponse, resonance reduction, lower distortion and an improved lowfrequency bandwidth. The internal structure of the housing reduces rearwaves and resonance to near free air characteristics. In addition, thepresent invention includes a line source with a relatively narrowaperture that provides an increased percentage of direct versusreflected sound for improved listening pleasure in a larger listeningarea within a room. Furthermore, the speaker system of the presentinvention preferably does not crossover within the frequency range ofabout 60-6,000 Hz. This provides improved spatial cues to a listener.Historically, rooms shapes have presented great placement challenges forthe listener. Notably, the speaker system of the present invention hasfrequency and dynamic linear dispersion that provides a robust systemlargely unaffected by room shapes, irregularities and anomalies.

[0010] These and other objects, features and advantages of the presentinvention will become apparent in light of the following detaileddescription of preferred embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a functional illustration of a speaker system;

[0012]FIG. 2 is a pictorial illustration of the mid-range/tweeter arrayof the speaker system;

[0013]FIG. 3 is a side view of the mid-range/tweeter array illustratedin FIG. 2;

[0014]FIG. 4 is a functional block diagram illustration of the mid-rangeand tweeter arrangement within the mid-range/tweeter array;

[0015]FIG. 5 is a schematic illustration of the mid-range/tweeter array;

[0016]FIG. 6 illustrates a cross-sectional view of the mid-range/tweeterarray taken along line 6-6 illustrated in FIG. 2;

[0017]FIG. 7 illustrates another cross-sectional view of themid-range/tweeter array taken along line 7-7 illustrated in FIG. 2;

[0018]FIG. 8 is a simplified cut-a-way side view of the woofer unit; and

[0019]FIG. 9 illustrates an alternative embodiment speaker system.

DETAILED DESCRIPTION OF THE INVENTION

[0020]FIG. 1 is a functional illustration of a speaker system 10. Thesystem 10 includes an input 12 that receives an input signal from asource (e.g., a stereo receiver, a CD player, etc). The input signal isrouted along two paths. The first path includes a high pass filter (HPF)13 (e.g., a series connected capacitor) that provides a high passedsignal to an amplifier 14, which provides an amplified signal to aplurality of mid-range/tweeter arrays(s) 15. The first path alsoincludes an impedance matching network 16. The impedance matchingnetwork 16 includes a plurality of selectable impedance values in orderto account for different amplifier manufacturer/model input impedance.The second path includes an equalizer circuit 18 that provides anequalized signal on a line 20 to an amplifier 21, which provides a lowfrequency amplified signal to woofer units 22.

[0021]FIG. 2 is a pictorial illustration of the mid-range/tweeter array15. Although only one array is illustrated, the system preferablyincludes two mid-range/tweeter arrays that are mirror imaged pairs. Themid-range/tweeter array 15 (e.g., the right speaker of the mirror imagedpair) includes a rigid housing 22, a plurality of mid-range drivers(e.g., 24-26) and a plurality of tweeters (e.g., 28-30). The housing 22may be constructed of wood, or molded or fabricated polymer. The moldedpolymer may be densified with non-resonant material. In general, thehousing should be relatively rigid and to-reduce standing waves andresonances within the housing.

[0022] It contemplated that the housing may also be formed from of aresin impregnated carbon fiber kevlar mix, that may also include balsawood or fiber glass. Aluminum and epoxy honeycomb may also be suitablehousing materials.

[0023] The mid-range drivers 24-26 and the tweeters 28-30 are preferablyarranged in a planar surface of the housing. The mid-range drivers 24-26are preferably in a first column 32, while the tweeters are arranged ina second column 34. Each of the mid-range drivers operates fromapproximately 60 Hz to 6 kHz, while the tweeters operate from about 6kHz to 30 kHz, without noticeable crossover.

[0024]FIG. 3 is a side view of the mid-range/tweeter array 15illustrated in FIG. 2.

[0025] Referring again to FIG. 2, in a preferred embodiment themid-range/tweeter array 15 is partitioned into a plurality of sub-arrays40-46. Referring now to FIGS. 2 and 4, each sub-array is furtherpartitioned into a tweeter sub-array (e.g., 47 a-47 c) and a mid-rangesub-array (e.g., 49 a-49 c). Each of the mid-range sub-arrays iselectrically parallel to one another, while each of the tweetersub-arrays is parallel to one-another.

[0026]FIG. 5 is a schematic illustration of the mid-range/tweetersub-array 40. The signal input to the sub-array 40 is routed to both thetweeter sub-array 47 a and the mid-range sub-array 49 a. The tweetersub-array 47 a includes a capacitor C, 50 that attenuates low frequencysignal components to provide a high-pass signal on a line 51. Aninductor L₁, 52 is located in parallel with a plurality of seriesconnected tweeters 53. The mid-range sub-array 49 a includes a resistorR₁ 54, an inductor L₂ 55 and a plurality of series connected mid-rangedrivers 56. Significantly, this arrangement provides multipleelectrically parallel sub-arrays, wherein each of the speakers within asub-array are electrically in series. The details regarding thecharacteristics and number speakers within a sub-array shall now bediscussed.

[0027] The mid-range speakers within the mid-range sub-array 56preferably have a relatively small moving mass, large magnets and a lowquality factor (i.e., a low “Q” factor). The number of individualmid-range speakers within the sub-array 56 is selected so the totalQ-factor for the sub-array is approximately one. The Q-factor for thesub-array is the sum of the individual speaker Q-factors multiplied by{square root}{square root over (2)}. For example, if the individualmid-range speakers have a Q-factor of about 0.21 then the sub-arraypreferably has three mid-range speakers since (0.21+0.21+0.21)×{squareroot}{square root over (2)} is equal to 0.89. If the sub-array 56 hadfour electrically connected speakers then the resultant Q-factor for thesub-array would be 1.19. Therefore, three is the preferred number ofspeakers in each mid-range sub-array for a mid-range speaker with a Qequal to 0.21. The {square root}{square root over (2)} multiplierrepresents the factor associated with a speaker system having optimalcabinetry. The mid-ranges may be woven carbon fiber units. A Q of one isequal to free air.

[0028] Referring still to FIG. 5, the tweeters within the tweetersub-array 53 are selected primarily based upon their bandwidth andaperture size. In addition, the tweeters are preferably silk domed. Asshown in FIG. 2, there are two tweeters mounted adjacent to eachmid-range. The tweeters are also arranged in a series/parallelconfiguration. For example, in one embodiment a plurality of tweeters(e.g., six) are connected in series in the tweeter sub-array, and eachtweeter sub-array (e.g., 47 a, 47 b and 47 c) is connected electricallyin parallel to the other tweeter sub-arrays. For example, there may be atotal of forty-two tweeters in the mid-range/tweeter array 15 (FIGS. 1and 2), arranged into seven electrically parallel tweeter sub-arrays(e.g., FIG. 2, 40-46) and each comprising six tweeters that areelectrically in series. One of ordinary skill will recognize thatvarious series/parallel combinations of the tweeters is possible. Ingeneral, it is desirable to have a large number of tweeters. Inaddition, the tweeters and mid-ranges are mounted within the front panelin order to reduce/minimize defraction and horn loading effects.

[0029]FIG. 6 illustrates a cross-sectional view of the array taken alongline 6-6 illustrated in FIG. 2 to illustrate the structure of themid-range/tweeter array housing (the mid-range and tweeters are notshown in this view in the interest of ease of illustration). The housingincludes a medium density fiberboard panel 60 and a first solid surfacepanel 62 (e.g., CORIAN™ or a CORIAN™ type material, or an ultra-highmolecular weight polymer, etc.), which are joined with a bonding layer(not shown) located between the two panels 60, 62. As shown in FIG. 1the fiberboard panel 60 and the first solid surface panel 62 include aplurality of opening for the mid-ranges and tweeters. The housing alsoincludes exterior side panels 64, 66 of, for example, medium densityfiberboard. The housing may also include a wood veneer wrap (not shown)that is mounted to the exterior side panels 64, 66 (e.g., mounted with aurea resin bonding layer—not shown). The housing also includes anexterior back wall 67 of medium density fiberboard. A second solidsurface panel 68 may be located inside of the exterior back wall 67 andjoined to the back wall with a bonding layer (not shown). The interiorsides of the exterior side panels 64, 66 are each mounted to mediumdensity fiberboard panels 70, 72 respectively.

[0030] The housing also includes shaped medium density fiberboard blocks74, 76 and a hemispherical concave interior wall 78. The hemisphericalwall 78 may be formed of polyvinyl chloride (PVC), which provides noparallel surfaces to sounds radiating into the hemispherical wall 78. Atuned, dampening bisector 80 is mounted to the hemispherical concaveinterior wall 78. The bisector 80 is preferably located at the center ofthe hemispherical concave interior wall 78. First and second interiorsidewalls 82, 84 are segmented and a first segment 86 extends from frontto back of the housing and preferably taper inward from back to frontalong the majority of the sidewall length. The first and second interiorsidewalls 82, 84 each mate with the hemispherical concave interior wall78. Second segments 90, 92 of the interior sidewalls 82, 84respectively, taper outward. High density particle board 94 is locatedbetween the first and second interior sidewalls and the medium densityfiberboard panels 70, 72. A plurality of vertically spaced lateralsupports (e.g., support 96) are also included for increased unitrigidity. The lateral supports may be expandable and contractible toincrease or decrease the separation of the sidewalls 82, 84. Thisfeature allows a user to adjust the separation in order vary the speakercharacteristics.

[0031] Acoustical attenuating material 97 is located within theremaining open spaces of the speaker to attenuate rear waves (i.e., wavelaunches toward the back of the housing). The acoustical attenuatingmaterial preferably comprises multiple fibers. The multiple fibers mayinclude 80% cotton and 20% dacron. These percentages arepercent-by-weight (PBW). An alternative material composition is 10%acrylic, 30% wool and 60% cotton fibers PBW. One of ordinary skill willrecognize that there are many alternative acoustical attenuatingmaterials that may be utilized.

[0032]FIG. 7 illustrates another cross-sectional view of the array takenalong line 7-7 illustrated in FIG. 2. Notably, this view illustrates thepositioning of the mid-range speaker 70 and the tweeter 72 within thehousing. It should be noted that the view set forth in FIG. 2 has thetweeters and mid-ranges positioned on opposite sides from the views setforth in FIG. 7. FIG. 2 represents the right mid-range/tweeter array(tweeters preferably on the outside) while FIG. 7 represents the leftmid-range/tweeter array.

[0033]FIG. 8 is a simplified cut-a-way side view of the woofer unit 22.The unit 22 includes two woofers 90, 92 that are wired out of phase withrespect to one another in a push-pull configuration. The first woofer 90(e.g., an 18″ woofer) is mounted in the upper region of the wooferhousing such that the front of the first woofer 90 is open to theoutside air. In contrast, the second woofer 92 is mounted in the lowerregion of the woofer housing and the rear of the second woofer 92 isopen of the outside air. That is, the front of the second woofer facesan interior chamber 94 of the woofer unit 22 that includes an acousticalattenuating material/stuffing 95 that is retained between webbing 97,99. The woofers 90, 92 are mounted within a cylindrical housing 96(e.g., a PVC pipe) to provide a cylindrical cartridge that is mountedinto a woofer housing 98. For example, the cylindrical cartridge may belocated within a cylindrical woofer housing or a rectangular wooferhousing. The woofer also includes a bisector 101 that extends across thecylindrical housing 96, preferably coaxial with the cylindrical housing.

[0034] The mid-range/tweeter array 15 (FIG. 2) provides a line sourcethat moves a large volume of air while retaining a relatively rapidtransient speed, concurrent with temporal accuracy having very accuratetime and phrase response with a large dynamic range. Historically, theproblem of large sound pressure level (SPL) delta over a broad band(dynamic linearity) was addressed utilizing horn loading techniques.However, temporal linearity was virtually negated. That is, there weretime and phase problems associated with the horns. The utilization ofmulti-driver optimal coupling versus large single driven (ribbon)technique affords enormous mass/motor ratio advantage. Optimal couplingof multi-driver arrays enables temporal anomaly cancellation by virtueof series anti-phase electrical coupling concurrent with acoustical massloading of the rear waves. The present invention provides a generousutility of drivers complement that is relatively expensive, but reduceseffective moving mass to near vanishing levels.

[0035] This loudspeaker design launches a wavefront front with greatdynamic power and speed.

[0036] The ratio of direct reflected signals is important for near-fieldeffect. The phase and timing of signals reaching the listener arecorrect giving space queues to the listener better than other designs.Near-field effect means the direct signal reaches the listener beforeany reflections.

[0037] The multiple mid-range drivers work from approximately 65 to6,000 Hertz with essentially no crossover.

[0038] The internal wiring harness is important due to its complexity inseries/parallel wiring of so many drivers. Impedance over frequencychanges, effecting the sensitivity so this configurationcancels/minimizes this negative characteristic of all speakers incomparison to prior art systems that use a small number of drivers withconventional crossover. A preferred wire for this design is a hollowTeflon® tube with a helix litz braid woven over the tube. These can becombined for multiple conductors and woven or wound to tune impedance,capacitance and resistance.

[0039] Electrostatic ribbon or other flat panels or arrays are verydirectional and the listener must sit precisely in the “sweet spot” atthe focal point of the two speakers in the listening room. However, thesystem of the present invention creates a much larger listening “sweetspot”.

[0040]FIG. 9 illustrates an alternative embodiment speaker system 100.The system 100 is generally arranged in the form a picture frame.Vertical legs 102, 104 of the system 100 include a plurality of speakersub-arrays (e.g., 106-108) similar to the sub-arrays illustrated in FIG.4.

[0041] Each of the speakers/drivers of the same type (i.e., mid-rangeversus tweeter) in the sub-arrays 106-108 are wired in series, whileeach of the sub-arrays of the same type are electrically parallel to oneanother. Significantly, this provides multiple electrically parallelsub-arrays, wherein each of the speakers within a sub-array areelectrically in series. The embodiment illustrated in FIG. 9 is similarto the embodiment illustrated in FIG. 2, with the exception that theembodiment in FIG. 9 does not include a deep housing comprising ahemispherical concave interior wall (e.g., element 78 in FIG. 5).Specifically, referring to FIG. 6, it is contemplated that thealternative embodiment speaker system would include a rear wallgenerally along a line A-A 120. The rear wall may include smalldiscontinuities in order to deflect the rear waves and break-up standingwaves within the housing. Notably, this alternative embodiment speakersystem may be mounted to a wall adjacent to a flat panel display for ahome theatre system, or as shown in FIG. 9 around a flat panel display.

[0042] Although the present invention has been shown and described withrespect to several preferred embodiments thereof, various changes,omissions and additions to the form and detail thereof, may be madetherein, without departing from the spirit and scope of the invention.

1. A speaker system, comprising: a housing that includes a front wallwith a plurality of openings, and first and second exterior sidewalls; aplurality of vertically arranged speakers each placed into an associatedone of said plurality of openings and secured to said housing; and ahemispherical concave interior wall positioned in back of said pluralityof speakers and within said first and second exterior sidewalls.
 2. Thespeaker system of claim 1, wherein said openings include a plurality ofmid-range openings and at least one tweeter opening adjacent to anassociated one of said mid-range openings.
 3. The speaker system ofclaim 1, further comprising: a rear exterior wall that defines a back ofsaid speaker system, wherein said front wall defines a front of saidspeaker system; and first and second interior sidewalls that taperinward in the direction of back to front of said speaker system, whereinsaid first and second interior sidewalls each mate with saidhemispherical concave interior wall.
 4. The speaker system of claim 1,wherein said hemispherical concave interior wall comprises a polyvinylchloride material.
 5. The speaker system of claim 1, further comprisinga bisector mounted to said hemispherical concave interior wallpositioned in back of said plurality of speakers and within said firstand second exterior sidewalls.
 6. The speaker system of claim 1, whereinsaid speakers include a plurality of mid-range speakers and a pluralityof tweeters, wherein said mid-range speakers are arranged in aseries/parallel electrical configuration including a plurality ofspeaker sub-arrays each electrically in parallel with one another, andeach of said plurality of speaker sub-arrays comprising a plurality ofmid-range speakers electrically in series.
 7. The speaker system ofclaim 6, wherein each of said mid-ranges speakers within a sub-array hasan associated quality (Q) factor, and sum of the quality factors forsaid mid-range speakers within a sub-array is approximately equal to1/{square root}{square root over (2)}.
 8. The speaker system of claim 6,wherein each of said mid-ranges speakers within a subarray has anassociated quality (Q) factor, and sum of the quality factors for saidmid-range speakers within a sub-array is in the range of about 0.5 to0.9.
 9. The speaker system of claim 1, further comprising: a rearexterior wall that defines a back of said speaker system, wherein saidfront wall defines a front of said speaker system; and first and secondinterior segmented sidewalls, each comprising a first segment thattapers inward in the direction of back to front, wherein said first andsecond interior sidewalls each mate at first ends thereof with saidhemispherical concave interior wall.
 10. A speaker system, comprising: ahousing that includes a front wall with a plurality of openings, andfirst and second exterior sidewalls; a plurality of vertically arrangedspeakers each placed into an associated one of said plurality ofopenings and secured to said housing, wherein said speakers arepartitioned into a plurality of sub-arrays, wherein said sub-arraysincludes a plurality of series connected speakers and said sub-arraysare arranged electrically parallel to one another; and a hemisphericalconcave interior wall positioned in back of said plurality of speakersand within said first and second exterior sidewalls.
 11. The speakersystem of claim 10, wherein said sub-arrays comprise: a plurality ofmid-range sub-arrays each comprising a plurality of series connectedmid-range speakers each having an associated Q-factor, wherein the sumof said associated Q-factors is equal to about is in the range of about0.5 to 0.9, and each of said plurality of mid-range sub-arrays iselectrically parallel to one another; and a plurality of tweetersub-arrays each comprising a plurality of series connected tweeters, andeach of said plurality of tweeter sub-arrays is electrically parallel toone another.
 12. The speaker system of claim 11, further comprising awoofer unit that includes a cylindrical housing comprising a firstwoofer and a second woofer arranged in a push-pull configuration. 13.The speaker system of claim 12, wherein said woofer unit furthercomprises a bisector within said cylindrical housing and co-axial withsaid cylindrical housing, wherein said bisector extends between saidfirst and second woofers.